diff --git a/src/libextra/test.rs b/src/libextra/test.rs
index 91db9302f6414..1658bb5f1614e 100644
--- a/src/libextra/test.rs
+++ b/src/libextra/test.rs
@@ -31,7 +31,6 @@ use treemap::TreeMap;
 use std::clone::Clone;
 use std::comm::{stream, SharedChan, GenericPort, GenericChan};
 use std::libc;
-use std::either;
 use std::io;
 use std::result;
 use std::task;
@@ -127,8 +126,8 @@ pub type MetricDiff = TreeMap<~str,MetricChange>;
 pub fn test_main(args: &[~str], tests: ~[TestDescAndFn]) {
     let opts =
         match parse_opts(args) {
-          either::Left(o) => o,
-          either::Right(m) => fail!(m)
+            Ok(o) => o,
+            Err(msg) => fail!(msg)
         };
     if !run_tests_console(&opts, tests) { fail!("Some tests failed"); }
 }
@@ -169,7 +168,7 @@ pub struct TestOpts {
     logfile: Option<Path>
 }
 
-type OptRes = Either<TestOpts, ~str>;
+type OptRes = Result<TestOpts, ~str>;
 
 fn optgroups() -> ~[getopts::groups::OptGroup] {
     ~[groups::optflag("", "ignored", "Run ignored tests"),
@@ -228,7 +227,7 @@ pub fn parse_opts(args: &[~str]) -> OptRes {
     let matches =
         match groups::getopts(args_, optgroups()) {
           Ok(m) => m,
-          Err(f) => return either::Right(getopts::fail_str(f))
+          Err(f) => return Err(getopts::fail_str(f))
         };
 
     if getopts::opt_present(&matches, "h") { usage(args[0], "h"); }
@@ -274,7 +273,7 @@ pub fn parse_opts(args: &[~str]) -> OptRes {
         logfile: logfile
     };
 
-    either::Left(test_opts)
+    Ok(test_opts)
 }
 
 pub fn opt_shard(maybestr: Option<~str>) -> Option<(uint,uint)> {
@@ -1155,7 +1154,6 @@ mod tests {
                StaticTestName, DynTestName, DynTestFn};
     use test::{TestOpts, run_test};
 
-    use std::either;
     use std::comm::{stream, SharedChan};
     use tempfile;
     use std::os;
@@ -1236,8 +1234,8 @@ mod tests {
     fn first_free_arg_should_be_a_filter() {
         let args = ~[~"progname", ~"filter"];
         let opts = match parse_opts(args) {
-          either::Left(o) => o,
-          _ => fail!("Malformed arg in first_free_arg_should_be_a_filter")
+            Ok(o) => o,
+            _ => fail!("Malformed arg in first_free_arg_should_be_a_filter")
         };
         assert!("filter" == opts.filter.clone().unwrap());
     }
@@ -1246,8 +1244,8 @@ mod tests {
     fn parse_ignored_flag() {
         let args = ~[~"progname", ~"filter", ~"--ignored"];
         let opts = match parse_opts(args) {
-          either::Left(o) => o,
-          _ => fail!("Malformed arg in parse_ignored_flag")
+            Ok(o) => o,
+            _ => fail!("Malformed arg in parse_ignored_flag")
         };
         assert!((opts.run_ignored));
     }
diff --git a/src/libextra/workcache.rs b/src/libextra/workcache.rs
index bbb8dbfcbfe53..aeec4b4258b39 100644
--- a/src/libextra/workcache.rs
+++ b/src/libextra/workcache.rs
@@ -19,7 +19,6 @@ use arc::{Arc,RWArc};
 use treemap::TreeMap;
 use std::cell::Cell;
 use std::comm::{PortOne, oneshot};
-use std::either::{Either, Left, Right};
 use std::{io, os, task};
 
 /**
@@ -252,9 +251,9 @@ struct Exec {
     discovered_outputs: WorkMap
 }
 
-struct Work<'self, T> {
-    prep: &'self Prep<'self>,
-    res: Option<Either<T,PortOne<(Exec,T)>>>
+enum Work<'self, T> {
+    WorkValue(T),
+    WorkFromTask(&'self Prep<'self>, PortOne<(Exec, T)>),
 }
 
 fn json_encode<T:Encodable<json::Encoder>>(t: &T) -> ~str {
@@ -426,7 +425,7 @@ impl<'self> Prep<'self> {
             db.prepare(self.fn_name, &self.declared_inputs)
         };
 
-        let res = match cached {
+        match cached {
             Some((ref disc_in, ref disc_out, ref res))
             if self.all_fresh("declared input",&self.declared_inputs) &&
                self.all_fresh("discovered input", disc_in) &&
@@ -434,7 +433,7 @@ impl<'self> Prep<'self> {
                 debug!("Cache hit!");
                 debug!("Trying to decode: %? / %? / %?",
                        disc_in, disc_out, *res);
-                Left(json_decode(*res))
+                Work::from_value(json_decode(*res))
             }
 
             _ => {
@@ -453,10 +452,9 @@ impl<'self> Prep<'self> {
                     let v = blk(&mut exe);
                     chan.send((exe, v));
                 }
-                Right(port)
+                Work::from_task(self, port)
             }
-        };
-        Work::new(self, res)
+        }
     }
 }
 
@@ -465,16 +463,18 @@ impl<'self, T:Send +
        Decodable<json::Decoder>>
     Work<'self, T> { // FIXME(#5121)
 
-    pub fn new(p: &'self Prep<'self>, e: Either<T,PortOne<(Exec,T)>>) -> Work<'self, T> {
-        Work { prep: p, res: Some(e) }
+    pub fn from_value(elt: T) -> Work<'self, T> {
+        WorkValue(elt)
+    }
+    pub fn from_task(prep: &'self Prep<'self>, port: PortOne<(Exec, T)>)
+        -> Work<'self, T> {
+        WorkFromTask(prep, port)
     }
 
     pub fn unwrap(self) -> T {
-        let Work { prep, res } = self;
-        match res {
-            None => fail!(),
-            Some(Left(v)) => v,
-            Some(Right(port)) => {
+        match self {
+            WorkValue(v) => v,
+            WorkFromTask(prep, port) => {
                 let (exe, v) = port.recv();
                 let s = json_encode(&v);
                 do prep.ctxt.db.write |db| {
diff --git a/src/libstd/logging.rs b/src/libstd/logging.rs
index 1b91276f904d6..db5edc2009e51 100644
--- a/src/libstd/logging.rs
+++ b/src/libstd/logging.rs
@@ -12,9 +12,8 @@
 
 use option::*;
 use os;
-use either::*;
 use rt;
-use rt::logging::{Logger, StdErrLogger};
+use rt::logging::{Logger, StdErrLogger, OwnedString};
 
 /// Turns on logging to stdout globally
 pub fn console_on() {
@@ -57,12 +56,12 @@ fn newsched_log_str(msg: ~str) {
         match optional_task {
             Some(local) => {
                 // Use the available logger
-                (*local).logger.log(Left(msg));
+                (*local).logger.log(OwnedString(msg));
             }
             None => {
                 // There is no logger anywhere, just write to stderr
                 let mut logger = StdErrLogger;
-                logger.log(Left(msg));
+                logger.log(OwnedString(msg));
             }
         }
     }
diff --git a/src/libstd/rt/logging.rs b/src/libstd/rt/logging.rs
index 0dd096b5bf352..d0bbf5c0506dc 100644
--- a/src/libstd/rt/logging.rs
+++ b/src/libstd/rt/logging.rs
@@ -7,7 +7,6 @@
 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
-use either::*;
 use libc::{uintptr_t, exit, STDERR_FILENO};
 use option::{Some, None, Option};
 use rt::util::dumb_println;
@@ -168,14 +167,20 @@ fn update_log_settings(crate_map: *u8, settings: ~str) {
     }
 }
 
+/// Represent a string with `Send` bound.
+pub enum SendableString {
+    OwnedString(~str),
+    StaticString(&'static str)
+}
+
 pub trait Logger {
-    fn log(&mut self, msg: Either<~str, &'static str>);
+    fn log(&mut self, msg: SendableString);
 }
 
 pub struct StdErrLogger;
 
 impl Logger for StdErrLogger {
-    fn log(&mut self, msg: Either<~str, &'static str>) {
+    fn log(&mut self, msg: SendableString) {
         use io::{Writer, WriterUtil};
 
         if !should_log_console() {
@@ -183,14 +188,11 @@ impl Logger for StdErrLogger {
         }
 
         let s: &str = match msg {
-            Left(ref s) => {
-                let s: &str = *s;
-                s
-            }
-            Right(ref s) => {
-                let s: &str = *s;
-                s
-            }
+            OwnedString(ref s) => {
+                let slc: &str = *s;
+                slc
+            },
+            StaticString(s) => s,
         };
 
         // Truncate the string
diff --git a/src/libstd/sys.rs b/src/libstd/sys.rs
index c3a5afc1ec8d6..f7f7fef6fa093 100644
--- a/src/libstd/sys.rs
+++ b/src/libstd/sys.rs
@@ -136,12 +136,11 @@ impl FailWithCause for &'static str {
 
 // FIXME #4427: Temporary until rt::rt_fail_ goes away
 pub fn begin_unwind_(msg: *c_char, file: *c_char, line: size_t) -> ! {
-    use either::Left;
     use option::{Some, None};
     use rt::in_green_task_context;
     use rt::task::Task;
     use rt::local::Local;
-    use rt::logging::Logger;
+    use rt::logging::{Logger, OwnedString};
     use str::Str;
 
     unsafe {
@@ -164,7 +163,7 @@ pub fn begin_unwind_(msg: *c_char, file: *c_char, line: size_t) -> ! {
                          msg, file, line as int)
                 };
 
-                task.logger.log(Left(msg));
+                task.logger.log(OwnedString(msg));
             }
         } else {
             rterrln!("failed in non-task context at '%s', %s:%i",
diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs
index b5772a9eede2d..bcd5005492b1b 100644
--- a/src/libsyntax/parse/parser.rs
+++ b/src/libsyntax/parse/parser.rs
@@ -80,8 +80,6 @@ use parse::{new_sub_parser_from_file, ParseSess};
 use opt_vec;
 use opt_vec::OptVec;
 
-use std::either::Either;
-use std::either;
 use std::hashmap::HashSet;
 use std::util;
 use std::vec;
@@ -94,7 +92,6 @@ enum restriction {
     RESTRICT_NO_BAR_OR_DOUBLEBAR_OP,
 }
 
-type arg_or_capture_item = Either<arg, ()>;
 type item_info = (Ident, item_, Option<~[Attribute]>);
 
 /// How to parse a path. There are four different kinds of paths, all of which
@@ -936,7 +933,7 @@ impl Parser {
             let (explicit_self, d) = do self.parse_fn_decl_with_self() |p| {
                 // This is somewhat dubious; We don't want to allow argument
                 // names to be left off if there is a definition...
-                either::Left(p.parse_arg_general(false))
+                p.parse_arg_general(false)
             };
 
             let hi = p.last_span.hi;
@@ -1290,12 +1287,12 @@ impl Parser {
     }
 
     // parse a single function argument
-    pub fn parse_arg(&self) -> arg_or_capture_item {
-        either::Left(self.parse_arg_general(true))
+    pub fn parse_arg(&self) -> arg {
+        self.parse_arg_general(true)
     }
 
     // parse an argument in a lambda header e.g. |arg, arg|
-    pub fn parse_fn_block_arg(&self) -> arg_or_capture_item {
+    pub fn parse_fn_block_arg(&self) -> arg {
         self.parse_arg_mode();
         let is_mutbl = self.eat_keyword(keywords::Mut);
         let pat = self.parse_pat();
@@ -1308,12 +1305,12 @@ impl Parser {
                 span: mk_sp(self.span.lo, self.span.hi),
             }
         };
-        either::Left(ast::arg {
+        ast::arg {
             is_mutbl: is_mutbl,
             ty: t,
             pat: pat,
             id: ast::DUMMY_NODE_ID
-        })
+        }
     }
 
     pub fn maybe_parse_fixed_vstore(&self) -> Option<@ast::Expr> {
@@ -3500,7 +3497,7 @@ impl Parser {
 
     // parse the argument list and result type of a function declaration
     pub fn parse_fn_decl(&self) -> fn_decl {
-        let args_or_capture_items: ~[arg_or_capture_item] =
+        let args: ~[arg] =
             self.parse_unspanned_seq(
                 &token::LPAREN,
                 &token::RPAREN,
@@ -3508,11 +3505,9 @@ impl Parser {
                 |p| p.parse_arg()
             );
 
-        let inputs = either::lefts(args_or_capture_items.move_iter()).collect();
-
         let (ret_style, ret_ty) = self.parse_ret_ty();
         ast::fn_decl {
-            inputs: inputs,
+            inputs: args,
             output: ret_ty,
             cf: ret_style,
         }
@@ -3542,7 +3537,7 @@ impl Parser {
     fn parse_fn_decl_with_self(
         &self,
         parse_arg_fn:
-        &fn(&Parser) -> arg_or_capture_item
+        &fn(&Parser) -> arg
     ) -> (explicit_self, fn_decl) {
         fn maybe_parse_explicit_self(
             cnstr: &fn(v: Mutability) -> ast::explicit_self_,
@@ -3650,20 +3645,20 @@ impl Parser {
         };
 
         // If we parsed a self type, expect a comma before the argument list.
-        let args_or_capture_items;
+        let fn_inputs;
         if explicit_self != sty_static {
             match *self.token {
                 token::COMMA => {
                     self.bump();
                     let sep = seq_sep_trailing_disallowed(token::COMMA);
-                    args_or_capture_items = self.parse_seq_to_before_end(
+                    fn_inputs = self.parse_seq_to_before_end(
                         &token::RPAREN,
                         sep,
                         parse_arg_fn
                     );
                 }
                 token::RPAREN => {
-                    args_or_capture_items = ~[];
+                    fn_inputs = ~[];
                 }
                 _ => {
                     self.fatal(
@@ -3676,7 +3671,7 @@ impl Parser {
             }
         } else {
             let sep = seq_sep_trailing_disallowed(token::COMMA);
-            args_or_capture_items = self.parse_seq_to_before_end(
+            fn_inputs = self.parse_seq_to_before_end(
                 &token::RPAREN,
                 sep,
                 parse_arg_fn
@@ -3687,11 +3682,10 @@ impl Parser {
 
         let hi = self.span.hi;
 
-        let inputs = either::lefts(args_or_capture_items.move_iter()).collect();
         let (ret_style, ret_ty) = self.parse_ret_ty();
 
         let fn_decl = ast::fn_decl {
-            inputs: inputs,
+            inputs: fn_inputs,
             output: ret_ty,
             cf: ret_style
         };
@@ -3720,7 +3714,7 @@ impl Parser {
         };
 
         ast::fn_decl {
-            inputs: either::lefts(inputs_captures.move_iter()).collect(),
+            inputs: inputs_captures,
             output: output,
             cf: return_val,
         }